Smoke detector



p 1953 c. N. CAHUSAC EIAL 2,554,98

SMOKE DETECTOR Filed Sept. 8, 1949 '4 Sheets-Sheet 1 "'-'/IIIIIII/"')-'-5 I INVENTORS C4 nee/{cf N051. Cmvusn 6 mm FRANK B. ALLEN A T TOE/VIZ p l953 c. N; CAHUSAC ETAL 6 SMOKE DETECTOR Filed sept. a, 1949 4 Sheets-Sheet 2 INVENTORS CLARENCE N054 Oil/05A c BY AND FRANK 5. A4. L EN p 1953 c. N. cAHusAc EI'AL 2,654,082

SMOKE DETECTOR Filed Sept. s, 1949 4Sheets-She et :5

INVENTORS CLARENCE N051. CA us/1c BY 4N0 FRANAB-ALLE Y ("WWW Patented Sept. 29, 1953 SMOKE DETECTOR Clarence Noel Cahusac, Newark, and Frank B. Allen, Towaco, N. J., assignors to C-O-Two Fire Equipment Company, Newark, N. J a corporation of Delaware Application September 8, 1949, Serial No. 114,611

13 Claims. (01340-7837) The present invention relates to apparatus for detecting and indicating the presence of sus pended matter in fluids, the apparatus being particularly suitable for detecting the presence of smoke in a fluid stream.

Apparatus in accordance with the invention may be used, in addition to other purposes, for the detection of smoke in rooms or sections of industrial buildings, or in the compartments or holds of ships. The apparatus is arranged to ac tuate a fire extinguishing system and to give a smoke signal when the presence of smoke is indicated, the apparatus also being arrangedto actuate a trouble signal in the event of a malfunction of its principal parts. It is generally desirable that the signals be given at a remote location, such as at a central station or control room.

Apparatus of this type generally includes a source of light, means for bringing a stream of fluid such as smoke from the space to be protected into the light beam, means for indicating the presence of the smoke, and electric responsive means such as a relay for controlling the production of an audible or visible warning signal, or for actuating additional apparatus such as the fire extinguishing system.

It is very important that smoke detecting apparatus function properly at all times and that an indication be given if trouble should develop.

Further, it is important that the apparatus be constructed so as to minimize the possibility of a false warning being given or that an unnecessary discharge be had of a fire extinguishing system.

The present invention aims to provide smoke detecting apparatus in which means are provided to indicate any condition adversely affecting its proper operation.

Another object of the invention is to provide a smoke detector which is efiicient in operation and durable in use.

In accordance with the invention this is accomplished by providing a smoke detector having an improved circuit including means adapted to be actuated upon the occurrence of any condition wherein the apparatus will fail to operate properly. g

A feature of the invention is the provision of means whereby the apparatus will give a smoke alarm only if both smoke detecting photoelectric cells and balancing cells operate in a proper manner.

Another feature of the invention is the provision of means to indicate the improper operation of either of the smoke detector photoelectric ele- 2 ments or of either of the balancing photoelectric elements.

Still another feature of the invention is the provision of means whereby when any of the component parts are in any condition aifecting its proper operation, the trouble signal will be given separate and distinct from the alarm signal.

A further feature of the invention is the provision of circuit interrupting means arranged to be actuated by the opening of the door to the cabinet enclosing the apparatus so that there can be no accidental actuation of the central station alarm or accidental discharge of the fire extinguishing system while adjustments are being made on the apparatus.

Other objects and advantages of the invention .will be apparent from the following description and from the accompanying drawings which show, by way of examples, embodiments of the invention.

In the drawings: Figure l is a perspective view of an apparatus in accordance with the invention. A visual smoke detecting unit is shown positioned above .an audible smoke detecting unit and connected therewith by piping. The inlet pipe for the vis- .ual unit is shown broken away and may be extended to a space from which the air is to be tested for smoke. The cover of the audible .cabinet is opened and the cover of the smoke detecting compartment removed to expose the smoke detecting photoelectric elements.

Figure 2 is a sectional view taken along the line 2-2 of the visual unit shown in Figure 1.

Figure 3 is a front view of the audible unit of Figure 1.

Figure 4 is a sectional view taken along the line 44 of Figure 8.

Figure 5 is a wiring diagram of the apparatus shown in Figure 1.

Figure 6 is a front view of a modified form of the invention utilizing a simplified circuit.

Figure '7 is a wiring diagram of the apparatus shown in Figure 6.

Figure 8 is a detailed sectional view of the door switches shown in'Figures 1 and 6.

Referring to the drawings there is shown a smoke detector I0 in accordance with the invention comprising a visual detector I I and an audible detector I2 connected by a pipe M. The term visual detector is used herein to distinguish from the audible detector, it being understood that in the visual detector when smoke is present it actually is seen due to light reflected by suspended smoke particles in the fluid. In the audible detector electro-mechanical means are employed, such as photoelectric cells, to indicate the presence of smoke in the fluid being tested, the indication thereof being given in the form of an alarm as by the sounding of a gong or by the lighting of a signal lamp.

The visual detector H has an inlet pipe I! shown broken away but which may lead to any space to be protected and from which samples of air are to be drawn for testing for smoke. The visual detector may be an individual unit as illustrated, or it may be constructed as a, plurality of units each having a pipe l5 leading to a separate space to be protected, the outlets from all of the visual detectors being manifolded to the pipe M to the audible detector. As shown, the individual smoke detecting unit I I comprises a housing enclosing a visual electric light source l1, and a lens I 9 used to concentrate and project light from the source 11 through the visual testing compartment 20. The smoke is brought into the visual testing compartment 26 through the pipe is and ejected through the pipe l4 into the audible testing detector II. A viewing window 2| made of a transparent material is positioned in one side or the visual testing compartment 26 at the side of the light beam projected through the lens I9. The inside or the detecting compartment 26 is painted or otherwise covered with a. dark non-reflecting material so that normally no light may be seen through the window 21 However, when smoke is present in the detecting chamber, light is reflected from the particles of smoke and may be observed through the window. Because 01' the concentration of the beam of light by the lens I9, a very small percentage of smoke in the air being tested is readily visible through the window 2|.

The audible detector is encased in a cabinet 22 having a swinging door 24 providing easy access to the mechanism within the cabinet. A transformer 25 is mounted on the top of the cabinet and connected to the apparatus in the interior thereof by suitable conduit means. Within the cabinet 22 is an audible smoke detector housing 26 having an inlet 21 connected with the pipe l4. The outlet of the audible smoke detecting compartment 26 leads to the inlet of the suction blower 29 which may have its outlet 60 either within the cabinet 22 or piped to the outside as may be desired. A sensitive relay panel 3| is positioned in front or the smoke detecting cabinet 26 in alignment with a transparent window 32 in the door 24. A pair of boxes 34 and 35 are used to enclose relays to be hereinafter described. An electrical power supply is connected through fuses 36 and 31 to a main switch 39. An audible smoke detector lamp 40 is positioned at one side of the smoke detecting housing 26 to project light therethrough by means of a suitable lens system 4|. Within the housing 26 are located a pair of detecting photoelectric elements or cells 43 and 44. A pair of balancing photoelectric elements or cells and 46 is positioned outside the housing 26 and connected in a circuit which will be later described.

The audible detecting housing 26 may be made of any suitable material such as sheet metal and is preferably provided with a removable cover 41 for inspection and cleaning of the interior thereof. The detecting photoelectric cells 43 and 44 located within the housing 26 are positioned at an angle with respect to each other and facing the path of the beam of light. by the 4 lens 4| into the smoke detector compartment. The pair of balancing photoelectric cells 45 and 46 are supported by a bracket 49 and are positioned at one side of and below the light 40 to avoid a high concentration of rays of light on the face of the cells. Any suitable means may be used for varying the amount of light received by the cells such as a semi-transparent glass cover, a diaphragm shutter, or the like, so that a balance may be had as will be later described.

The blower 29 is actuated by a motor 50 to produce a negative pressure within the piping system and smoke detector compartment. An indication of a failure of the blower is given by a suction actuated switch 5| inserted ahead of the blower 29.

An indicating light 52 is supported within the cabinet l2 in juxtaposition with a window 54 in the door 24 to indicate the energization of the unit.

The wiring diagram of the smoke detector I0, is shown in Figure 5. A pair of smoke detecting units is formed of the photoelectric cells, one unit comprises the detecting cell 43 connected in opposition with the balancing cell 45 and in series with a. resistance 55, while the other unit comprises the detecting cell 44 connected in opposition with the balancing cell 46 and in series with a resistance 56. The outputs of the detecting cells for the two units are respectively connected to coils 51 and 56 of sensitive relays 66 and 6|. The sensitive relays include double throw switches having movable elements 62 and 64, trouble signal contacts 65 and 66 and smoke signal contacts 61 and 68.

The trouble contact 65 of the sensitive relay 60 is connected by a wire 10 to one terminal of a double coil detecting cell supervisory relay 1| having a relay coil 12 connected by a wire 13 to a common ground 14. The supervisory relay 1| is adapted to indicate trouble in either or both of the detecting cells 43 and 44. The trouble contact of the sensitive relay 6| is connected by a. wire 15 to a second coil 16 of the relay 1|. The coil 16 has its other terminal connected by a lead 11 to one side 16 of a power supply protected by the fuse 86. In the event either of the detecting cells become open circuited or for any reason .tail to produce normal current output, its corresponding balancing cell causes the sensitive relay moveable contact to go to the trouble position. When either of the coils of the relay 1| are energized its contacts 19 and 60 are closed connecting a second power supply 8| protected by the fuse 31 to a trouble signal bus 62. A trouble signal lamp 64 and a trouble buzzer or gong 65 are connected between the trouble bus 62 and the power supply 6| in order to provide a trouble indication.

To provide a source of supply for the actuation of the relay 1| by its coil 12 a wire 66 is connected between the power supply 11 and the movable element 62 or the sensitive relay 60. The relay 1| is actuated by its other coil 16 by making a ground oozmection through the movable element 54 of the other msitive relay 6| and a wire 61 to the common ground 14. While the relay 1| has been described as being a two coil relay, it is obvious that in an alternative construction a pair of single coil relays might be used each having their contacts 19 and connected in parallel so that either relay may actuate the trouble signal in the same manner as it .is now actuated by one of the coils of the r y 1..

A pair of balancing cell relays are provided for each of the sensitive relays, each balancing cell relay being adapted to actuate a plurality of switching contacts. These relays also cause the actuation of an alarm signal. The balancing cell supervisory relays are indicated by the numerals 89 and 99 and respectively have operating coils 9I and 92. The operating coil SI is connected to the smoke signal contact 61 of the sensitive relay 60, the operating coil having .its other contact connected by a wire 94 to the ground bus 14. The other supervisory relay 90 has one terminal of its coil 92 connected to the power supply 18 by a wire 95 while the other contact of the coil 92 is connected by a wire 96 to the smoke signal contact 68 of the sensitive relay 6I.

A smoke signal bell I and a smoke signal lamp I III are connected in parallel across a wire I04 connecting with the ground bus 14, the other sides of these devices are connected in parallel by a wire I05 to contact I06 of a smoke signal relay I01. The smoke signal relay I01 is used to avoid the necessity of providing the contacts of the balancing cell supervisory relays with high ca pacity current contacts. In an alternative construction the smoke signal bell and lamp might be directly connected to contacts of the balancing cell supervisory relay.

The smoke signal relay I01 is energized only upon the actuation of both of the balancing cell supervisory relays 89 and 90. This is accomplished by providing each of the supervisory relays 89 and 90 with a pair of double throw contacts having their movable elements connected in series and having their double throw contacts arranged in a parallel connection. The connection is so arranged that in the event only one of the relays 89 or 99 are actuated, a connection is made to the trouble signals. This is done by providing a series connection I69 between the movable element for relay 89 and a movable element III for the relay 90. Contact II2 of a double throw switch for the relay 89 is connected to a contact I I4 of a double throw switch of the relay 90 by a wire I I5, in turn, connected to the trouble bus 82 by a wire I16. The power supply 8I is connected by a wire II1 to another contact II9 of the double throw switch for the relay 90, in turn, connected by a wire I to the other contact I2I of the relay 89.

The power supply 18 is connected by a wire I22 to the movable element of a normally open single throw contact I24 of a normally open switch having its other contact I25 connected by a wire I26 to a movable element I21 of a single throw switch actuated by the relay 89 and its other contact I29 connected by a wire I30 to one terminal of an operating coil I 3| of the smoke signal relay I01, the operating coil I3I having its other terminal connected by a wire I32 to the ground bus 14.

In the connection in which the photoelectric cells are connected in opposition in series with a resistance, the resistances have the effect of increasing the sensitivity of the unit by reducing the effective output of the balancing cells. The detecting cells do not generate excess current unless smoke is present.

If it were possible to provide a detecting cabinet in which no stray light was present it would be unnecessary to use a balancing cell. How ever, as stray light is always present the balancing cells 45 and 46 are required and are connected in opposition with the detecting cells 43 and 44, and the outputs of the balancing cells 45 and 46 are adjusted so as to counteract the out- I66 having one terminal connected to the resistance I5I by a wire I61 and to the other side of the resistance by wire I69. A supervisory relay I1I to the power supply 8I and its other contact connected by a wire I12 to the trouble bus 92. I

pets of the detecting cells 43 and 44 under the effects of stray light. In the event smoke is present, the outputs of the detecting cells increase and initiate actuation of the smoke signal through the relays 89, and I01.

The photoelectric elements are inherently of slightly different characteristics thus making it diflicult to adjust both units so that they will actuate their smoke signal at practically exactly the same time. This is disadvantageous in that, unless provision is made otherwise, if either of the detecting cells calls for smoke, and the other does not, a trouble signal is given. This difficulty is overcome by providing a normally closed shorting switch for each of the resistances 55 and 56 so connected that the shorting switch for the resistance of one of the units is opened when the detecting cell for the other unit actuates its relay to the smoke signal position.

The resistance tends to effect an increase in the sensitivity of the unit by causing a voltage drop across the balancing cell and resistance in series thus lessening its opposition to the positive action of the circuit. Thus by opening the shorting switch a possible time lag is overcome and a smoke signal is given rather than a trouble alarm signal. y

The resistance 55 is connected by a pair of wires I34 and I35 connecting it to a normally closed single throw switch having contacts I36 and I31 and actuated by relay 89, while the resistance 56 has a pair of wires I39 and I40 connecting it toa normally closed single throw switch having contacts MI and I42 and actuated by the relay 92.

The audible detector is provided with a source of light such as the electric lamp 40 connected by wires I43 and I44 with the secondary I45 of a transformer I46. A primary winding I41 of the transformer I46 is connected by a wire I49 to the power supply 11 and by a wire I50 to the wire I04 connecting, in turn, to the ground bus 14. A resistance I5I is connected in series with the lamp 40 and is adapted to be shorted by single throw switches actuated by either relay 89 Or 99. A wire I52 from one side of the resistance IEI is connected to a contact I54 of the relay 89, in -turn, connected in a parallel connection with a contact I 55 of the relay 90 by a wire I56. The

other side of the resistance I 5I is connected by a wire I53 to a contact I59 of the relay 90, in turn, connected in a parallel connection with a contact I60 of the relay 89 by a wire I6I.

The resistance I5I is normally connected in intensity and thus add to its life. In order to wire I65 connected to the power supply 13, is adapted to periodically close a shorting switch I10 is connected in series with the timing control unit I62 and has its contacts connected by a wire The visual lamp I1 is connected to the power supply 18' by a lead I14 through a series resistance [15, the other terminal of the visual lamp is connected through the coil of a supervisory relay I 16 to the ground bus 14 by a wire I80.

The contacts of the supervisory relay I16 are con- I nected to the power supply 8| by a wire I11 and to the trouble bus 82 by a Wire I19. The visual lamp series resistance I is connected by a wire I8I to a normally open contact I82 of the smoke signal relay I01, and a corresponding contact I84 of the normally open switch is connected by a wire I85 to the other side of the resistance ii. The electric discharge plug I02 is connected by a wire I85 through a door switch I81 and a wire I89 to a contact I90 of a normally open switch having its other contact I9I connected by a Wire I92 to the wire 18. The door switch I81 is normally resiliently urged into the open position and is held closed by the door 24, thus eliminating the possibility of an accidental discharge of the fire extinguishing system while the door is open as for adjustments of the apparatus within the cabinet 22.

The blower 50 has one of its terminals connected with the power supply 18 by a wire I94 while its other terminal is connected by a wire I95 to the ground bus 14. The blower supervisory switch 5| has one of its contacts I36 connected by a wire I91 to the power supply BI while its other contact I99 is connected by a wire 2% to the trouble bus 82. The blower supervisory switch 5I is normally closed and is adapted to be actuated into the open position upon the cessation of the suction in the blower inlet.

A stop discharge relay I has its coil connected with the ground bus by a Wire 2202 and with the trouble bus by a wire 204, its contacts being connected in series with those of the door switch I81 so that in the event the trouble circuit is energized the electric discharge plug I02 is prevented from becoming energized and thus causing an unnecessary discharge of the system.

In the operation of the system of the smoke detector shown in Figure 5, the main switch 39 is closed energizing the system and causing the pilot indicating lamp 52 to light. The blower 58 is started providing suction to actuate the suction control switch 5| preventing the trouble signal, and at the same time the visual lamp I1 and the audible lamp 40 are lighted. The balancing cells and 46 are adjusted to produce the required output so that the midpoints 62 and 84 of the sensitive relays and BI are positioned intermediate their contacts. The system is then operating normally, the timing control unit I62 being energized to periodically short the resistance I5I for the audible lamp 40 so that its intensity is periodically increased to increase the sensitivity of the audio-detector.

In the event smoke is drawn into the housing 26, light from the audible lamp 40 is reflected from the smoke to the surface of the detecting cells 43 and 44. By reason of their inherent differences in characteristics, it is quite possible that one of the detecting units will have a larger output, and assuming this to be the case for the detecting cell 43, the sensitive relay BI will be operated so that the movable element 64 of the double throw switch is moved to the contact 68 energizing the coil 92 of the relay 90. The contacts of the relay 90 are actuated, contact I55 being connected with contact I59 to short the resistance ISI for the audible lamp therefore increasing its intensity tending to produce a greater output from the detecting cell 44. At the same time, the relay has opened contacts HI and I42 normally shorting resistance 56 thus giving the effect of further increasing the output of the detecting cell 44, contacts I24 and I25 are connected providing a source of supply to the contact I21 of the relay 89, and the movable element III of the double throw 8 switch is actuated from contact II! to the contact I I4.

In the event the system is operating properly, and smoke is present, by this time relay 44 will have actuated its sensitive relay 60 so that its movable element 62 is moved to the contact 61, thereby energizing coil 9| of the relay 89, actuating all of its contacts so that no trouble signal is given, the movable element IIII opening its connection with the contact I2I, simultaneously the contact I21 has been connected to the contact I29 energizing the smoke signal relay I01 and actuating its armature to close the contacts I93 and I8I respectively to the contacts I06 and I90, to energize the wires I05 and I89 from the power source 11.

The smoke signal bell I00 and the smoke signal lamp IOI are thus energized to give a signal, and the electric discharge plug I02 is energized to discharge the fire extinguishing medium into the protected space to complete a normal cycle of operation of the apparatus resulting from the presence of smoke. The energization of the smoke signal relay I01 causes the closing of its contacts I82 and I84 shorting the resistance I15 for the visual lamp I1, thereby increasing its intensity and thus giving a better visual indication of the presence of smoke.

Assuming there is no smoke present, and that the operation of the sensitive relay 6| is caused by a defect, for example, in the detecting photoelectric cell 43 causing an increase in its output. In this event, even though the intensity of the visual light 48 is increased and the resistance 56 is cut into the circuit decreasing the effect of the balancing cell 46, the output of the cell 44 is not increased enough to actuate the sensitive relay 68 to move its movable element 62 to its smoke signal contact 61. Thus the supervisory relay 89 is not actuated and its contact IIO remains connected to its contact I2I, thereby connecting the power circuit 8| through the wire I09, through the actuated contacts III and H4 through the lead III; to energize the trouble bus 82 to actuate the trouble lamp 84 and the trouble gong 85 to indicate that the system is operating defectively.

In the event either one of the detecting cells is defective in that its output is decreased a trouble signal will also be given. Assuming, for example, that the detecting cell 43 is defective and its output is decreased then its sensitive relay 6I is actuated so that the movable element 64 is connected to the contact 66 energizing the detecting cell supervisory relay TI to close its contacts to energize the trouble bus 82 from the power circuit 8I. It should be noted that the energization of the trouble bus 82 automatically energizes the stop discharge relay 20I so that the electric discharge plug I02 is prevented from becoming energized.

In the event either one of the balancing cells is defective in that its output is decreased a trouble signal will also be given. Assuming, for example, that the balancing cell 45 is to become defective and its output is decreased, then the same effect is produced as if the output of the detecting cell 43 had been increased. The sensitive relay BI is actuated so that the movable element I54 makes a connection with the contact 68 energizing the relay 90. As the relay 89 is not energized, a trouble signal is given by the completion of the circuit through the contacts III and IE4.

Referring to the embodiment of the invention shown in Figure 6-8, there is shown a smoke detector 2| 6 which differs from the embodiment shown in Figures 1-5 mainly in that only a single detecting and balancing cell unit is used. The supervision of the circuits is also simplified resulting in a smoke detector which may be produced at a lower cost for installations in which the added safeguards of the first embodiment are not warranted.

The detector 216 is encased in a housing or cabinet 222 having a door 224 providing access to the mechanism within the cabinet. A transformer 225 is mounted within the cabinet 222, together with an audible smoke detector housing 226 having an inlet 221. The outlet of the smoke detecting compartment 226 leads to the inlet of a suction blower 229. A sensitive relay panel 231 is positioned in front of the smoke detecting cabinet 226 and in alignment with a transparent window 232 in the door 224. A relay box 234 is positioned above the transformer 225.

A power supply is connected through fuses 236 and 231 to a main switch 239. An audible lamp 246 is positioned at one side of the smoke detector housing 226 and is adapted to project into the housing through a lens 2. Within the housing 226 is a detecting photoelectric element 243 connected in opposed relationship with a balancing photoelectric element 245 positioned outside of the housing 226 and in range of the light from the electric lamp 246. Suitable means are provided for varying the light to the balancing element 245 such as by the use of a shutter 246.

The blower 229 is actuated by a motor 256 to draw air to be tested for smoke through the smoke detector housing 226. A suction actuated switch 25! is connected into the inlet piping to the blower 229 at any suitable location, such as in the inlet 221.

The wiring diagram of the smoke detector 216 is shown in Figure '7. The photoelectric elements 243 and 245 are connected in opposed relationship and in parallel with a coil 251 of a sensitive relay 266. A movable element 262 of the sensitive relay 266 connects a ground wire 264 through a coil of a smoke signal relay 265 to one of the dual power supplies 266 and 261. A smoke signal lamp 269 is connected between the ground wire 264 through a movable element The movable element I A trouble lamp 281 and a trouble gong 262 are connected through a trouble bus 284 and the suction switch 25| through a wire 285 tothe power supply 266. The trouble bus 284 is also connected through a movable element 286 of an audible lamp supervisory relay having a coil 281 to the power supply 266. The blower motor 256 is connected by a wire 289 to the ground bus 264 and by a wire 296 to the power supply 261.

The audible lamp 246 is connected in the econdary of the transformer 225 in series with the coil 281 of its supervisory relay by wires 2!, 292 and 293. The transformer 225 is connected with the ground bus 264 by a wire 295 and with the power supply 261 by a wire 296.

In the operation of the smoke detector 2l6 it is connected to the electrical power supply by the switch 239. The sensitive relay 266 is adjusted by the manipulation of the shutter 246 of the balancing cell 245. In the event the audible lamp 246 is defective a trouble signal is given by the supervisory relay 281. Likewise, a trouble signal is given if the suction switch 25l indicates a lack of suction in the piping system such as by a failure of the blower 229 or its motor 256. The door switch 214 is actuated by the closing of the door 224 making the system ready for a discharge of the fire extinguishing system through its actuating element 216 upon the presence of smoke in the housing 226.

While the invention has been described and illustrated with reference to specific embodiments thereof, it wil lbe understood that other embodiments may be resorted to without departing from the invention. Therefore, the forms of the invention set out above should be considered as illustrative and not as limiting the scope of the following claims.

This application is a continuation-in-part of our co-pending application Serial No. 5,524 filed January 31, 1948.

We claim:

1. In apparatus for detecting smoke in a fluid, a visual light source to provide a visual indication of smoke, a visual light seriesresistance connected in a circuit with the visual light source to normally decrease the intensity of the visual light source, a trouble signal, a visual light supervisory relay to complete an electrical circuit to the trouble signal for indicating the operability of the visual light source, a suction blower, a suction conduit for conducting a stream of fluid into the apparatus, a suction actuated switch to complete an electrical circuit to the trouble signal for indicating the operability of the suction blower, an audible light source to provide an audible indication of smoke, a series resistance connected in a circuit with the audible light source to decrease the intensity of the audible light source, a timing switch connected across the audible light series resistance for periodically increasing the intensity of the audible light by by-passing the audible light series resistance, an audible light supervisory relay to complete an electrical circuit to the trouble signal to indicate the operability of the audible light source, a timing switch supervisory relay to complete an electrical circuit to the trouble signal for indicating the operability of the timing switch, a pair of detecting photo-electric cells adapted to receive light reflected from smoke in the fluid, a pair of balancing photo-electric cells, a pair of photo-electric cell resistances, each of the detecting and balancing cells connected inopposition and in series with one of the photoelectric cell resistances to form a pair of smoke detecting units, a pair of sensitive relays each electrically connected across one of the detecting cells, a sensitive relay double throw switch actuated by each sensitive relay, balancing means for each of the photo-electric cell units to vary their respective outputs to each of the sensitive relays so that the sensitive relay double throw switches are normally positioned intermediate their contacts, a detecting cell trouble signal supervisory relay for each sensitive relay adapted to complete an electric circuit to the trouble signal from one of the sensitive relay switch contacts, a balancing cell supervisory relay for each sensitive relay adapted to actuate a plurality of switching means, a trouble signal double throw switch for each balancing cell supervisory relay, series connection means between the midpoints of the trouble signal double throw switches of both said relays, connection means from the ii contacts of one balancing cell supervisory relay trouble signal double throw switch to the contacts of the other balancing cell supervisory V relay trouble signal double throw switch arranged in a reversed connection so that when either one of said relays is actuated a connection is made through the contacts controlled b the other of said relays to the trouble signal while if both of said relays are actuated the trouble circuit is opened, a smoke signal, a smoke signal relay, a normally open smoke signal relay single throw switch actuated by each of the balancing cell supervisory relays, series connection means for thesmokesignal relay single throw switches of both relays, the A smoke signal relay connected in series with the smoke signal relay sing e throw switches so that when both balancing cell supervisory relays are amifsteathe 'smoke signal relay is actuated, a "riially ores s'fr'ioke signal single throw switch "actuated by the smoke signal relay to complete an electrical circuit to the smoke signal, a pair of audible light resistance normally open single throw switches each actuated by a balancing "cell supervisory =ielay and both connected across the audible light series resistance, a pair of p'hdto electriccell resistance single throw normallyclosed switches'e'ach'actuatetl by a balancing cell siipe'rvisory relay, one or said last mentioned switches adapted to be actuated by one balancing cell supervisory relay and connected across the photo electriccell resistance for other balan'cing "cell supervisory relay, the other or "said last mentioned switches adapted to bea'ctiiatd by th'e-other'balancing cell supervisory relay andconnected across the photo-electric cellreBiBt'ance-fOr'theone balancing -cellsupervisory relaxant-electrical discharge means for a lire extinguishingsystem, 'a normally open single throw fire extinguishing system switch adapted to be actuated by -the smoke signal relay 'to complete an electric circult to actuate the electrical -discharg'e nieans,'a stop discharge rela connected *in parallel with the troublesignal, and a nornraily' closed single throw stop discharge switchactuated by -the stop discharge relay to open the electric discharge means circuit when=the trcublesignal is acts-axed.

2'. In aplifliatus forw'ietecting a fluid, a visual light'soii-rce-to providea visual-indication of smoke, a visual light series resistance connected in a circuit with the visual light source to normally decrease the 'intensity of-the'visual light source, "a 'trct'ibie signal-a suction blower, a swam conduit --fer conducting *ast'ream of fluid into the apparatus'an-a'udible lightsource 'to'provide an-audiblei'ndication of smokeja series resistance connetedin a circuit with-the audible light source to decrease "the intensity of the audible light 'sot'ircmn "timing s-imam connected across the audible light series resistance {or periodically increasing the intensity "of the audible lightbyby pass'ing the audible light'series resistance-a pair'of detecting photo 'eie'ctric cells at'i'apted-to i-eceive light reflected from smoke in the fluid, -a--pair-cfbalancing photo-electric cells, a pair of photo-electric cell resistances,"eachfot the detecting and balancing cells connected in opposition "and in series-with one of the photoelectric cell resistances 'to" foi'in"japair of smoke detecting units,-*apair of sen'sitite relays"each electrically connected across --one of the detecting cells, a sensitive relay'doubie 'throw"switeh actuatedbyeach-sensitive relay,'balancing means for each of the 'photo-=electric"cell' units'to vary their' respective outputs to each "of the sensitive relays so that 'the'sensitive 'rel'ay' double throw switches are normally positioned intermediate their contacts, a detecting cell trouble signal supervisory relay for each sensitive relay adapted to complete an electric circuit to the trouble signal from one of the sensitive relay switch contacts, a balancing cell supervisory relay for each sensitive relay adapted to actuate a pinrality'of switching means, a trouble signal double throw switch -for each balancing cell supervisory relay, series connection means between the midpoints of the trouble signal double throw switches of both said relays, connection means from the contacts of one balancing cell supervisory relay trouble signal double throwswitch .to the contacts of the other balanc'ing cell supervisory relay trouble signal double throw switch arranged in a reversed connection so that when either one of said relays are actuated a connection is made through the contacts controlled by the other 0! said relays to the trouble signal while if both of said relaysare actuated the trouble circuit is opened, a smoke signal, a smoke signal relay, a normally open smoke signal relay single throw switch actuated by each of the balancing cell supervisory relays, series connection means for the smoke signal relay single throw switches 01 both relays, the smoke signal relay connected in series with the smoke signal relay single'throw switchessothat whenboth balancing cell supervisory relays are wactuated the smoke signal relay is actuated, a normally open smoke signal single throw switch actuated by the smoke signal relay to complete an electrical circuit to the smoke signal, a pair of audible light resistance normally open single .throw switches each actuated by a balancing .cell supervisory relay and both connected across the audible light series resistance, a pair of photo-electric cell resistance single thrownormallyclosed switches each actuated by a balancing cell supervisory relay, one of said last mentioned switches adapted to be actuated by one balancing cell supervisory relay and connected across the photo-electric cell resistance for theother balancing cell supervisory relay, the other of said last mentioned switches adapted to be'actuated by the other balancing cell supervisory relay and connected across the photo-electric cell. resistance for the one balancing-cell supervisoryirelay a'n electrical discharge means for a-fire-extinguishing system, and a normally open single throw fire extinguishing .system switch adaptedtobe actuated by'the smoke signal relay to complete an electric circuit to actuate the electricalfdischarge means, a stop discharge relay connected in parallel with the trouble signal, and a normally closed single throw stop dischargeswitch actuated b the stop discharge relay to openthe electric discharge means circuit when the trouble signal is actuated.

3. In apparatus tondetecting smoke in a fluid, 'a troublesignal, a suction blower, a suction conwluitfor-conducting .a stream of fluid into the apparatus,- anaudible light source. to provide an audibleindication of smoke, a series resistance connected in a circuit with the audible light source to decrease the intensity of theaudible light source, a ti'mlng switch connected "across the audiblelight series resistance for periodically increasing' the mten'sity o'f theal1dib18i1lght :by

- by' pa'ssing the "audible light series resistance: a

pair of detectingpho'to eleetric :ciallsmdaptedzto 'receive li'ghtrefleeted rrom'-smoke inLthe fiuid, at detecting and balancing cells connectedm op- ,palr'ofbalancingphotmlectric cells, cachet the position to" form a pairot smoke detecting units,

a pair of sensitive relays each electrically con-- nected across one of the detecting cells, a sensitive relay double throw switch actuated by each sensitive relay, balancing means for each of the photo-electric cell units to vary their respective outputs to each of the sensitive relays so that the sensitive relay double throw switches are normally positioned intermediate their contacts, a detecting cell trouble signal supervisory relay for each sensitive relay adapted to complete an electric circuit to the trouble signal from one of the sensitive rela switch contacts, a balancing cell supervisory relay for each sensitive relay adapted to actuate a plurality of switching means, a trouble signal double throw switch for each balancing cell supervisory relay, series connection means between the midpoints of the trouble signal double throw switches of both said relays, connection means from the contacts of one balancing cell supervisory relay trouble signal double throw switch to the contacts of the other balancing cell supervisory relay trouble signal double throw switch arranged in a reversed connection that when either one of said relays are actuated a connection is made through the contacts controlled by the other of said relays to the trouble signal while if both of said relays are actuated the trouble circuit is opened, a smoke signal, a smoke signal relay, a normally open smoke signal relay single throw switch actuated by each of the balancing cell supervisory relays, series connection means for the smoke signal relay single throw switches of both relays, the smoke signal relay connected in series with the smoke signal relay single throw switches so that when both balancing cell supervisory relays are actuated the smoke signal relay is actuated, a normally open smoke signal single throw switch actuated by the smoke signal relay to complete an electrical circuit to the smoke signal, a pair of audible light resistance normally open single throw switches each actuated by a balancing cell supervisory relay and both connected across the audible light series resistance, an electrical discharge means for a fire extinguishing system, and a normally open single throw flre extinguishing system switch adapted to be actuated by the smoke signal relay to complete an electric circuit to actuate the electrical discharge means.

4. In apparatus for detecting smoke in a fluid, a trouble signal, a suction blower, a suction conduit for conducting a stream of fluid into the apparatus, an audible light source to provide an audible indication of smoke, a pair of detecting photo-electric cells adapted to receive light reflected from smoke in the fluid, a pair of balancing photo-electric cells, each of the detecting and balancing cells connected in opposition to form a pair of smoke detecting units, a pair of sensitive relays each electrically connected across one of the detecting cells, a sensitive relay double throw switch actuated by each sensitive relay, balancing means for each or" the photo-electric cells units to vary their respective outputs to each of the sensitive relays so that the sensitive relay double throw switches are normally positioned intermediate their contacts, a balancing cell supervisory relay for each sensitive relay adapted to actuate a plurality of switching means, a smoke signal, a normally open smoke signal single throw switch actuated by each of the balancing cell supervisory relays, series connection means for the smoke signal single throw switchs of both relays, the smoke signal connected in series with the smoke signal single throw switches so that when (all both balancing cell supervisory relays are actu ated the smoke signal is actuated, and a pair of audible light resistance normally open single throw switches each actuated by a balancing cell supervisory relay and both connected across the audible light series resistance.

5. In apparatus for detecting smoke in a fluid, a trouble signal, a suction blower, a suction conduit for conducting a stream of fluid into the apparatus, a light source to provide an indication of smoke, a pair of detecting photo-electric cells adapted to receive light reflected from smoke in the fluid, a pair of balancing photo-electric cells. each of the detecting and balancing cells connected in opposition to form a pair of smoke detecting units, a pair of sensitive relays each electrically connected across one of the detecting cells, a sensitive relay double throw switch actuated by each sensitive relay providing smoke and trouble signal contacts, balancing means for the photo-electric cell units to vary their respective outputs to each of the sensitive relays so that the sensitive relay double throw switches are normally positioned intermediate their contacts, a detecting cell trouble signal supervisory relay for each sensitive relay adapted to complete an electric circuit to the trouble signal from one of the sensitive relay contacts, and a smoke signal, the smoke signal contacts of both of the sensitive relays connected in series with the smoke signal so that when both of the sensitive relays are actuated to their smoke signal contacts a smoke signal is given.

6. In apparatus for detecting smoke in a fluid, a light source, a conduit for conducting a stream of fluid into the apparatus, a trouble signal, a smoke signal, a pair of detecting photo-electric cells adapted to receive light reflected from smoke in the fluid, a pair of balancing photo-electric cells, each of the detecting andbalancing cells connected in opposition to form a pair of smoke detecting units, a pair of sensitive relays each electrically connected across one of the detecting cells, a sen sitive relay double throw switch actuated by each sensitive relay, balancing means for each of the photo-electric cell units to vary their respective outputs to each of the sensitive relays so that the sensitive relay double throw switches are normally positioned intermediate their contacts, a balancing cell supervisory relay for each sensitive relay adapted to actuate a plurality of switching means, a trouble signal double throw switch for each balancing cell supervisory relay, series connection means between the midpoints of the trouble signal double throw switches of both said relays, connection means from the contacts of one balancing cell supervisory relay trouble signal double throw switch to the contacts of the other balancing cell supervisory relay trouble signal double throw switch arranged in a reversed connection so that when either one of said relays are actuated a connection is made through the contacts controlled by the other of said relays to the trouble signal while if both of said relays are actuated the trouble circuit is opened, a single throw smoke signal switch actuated by each of the balancing,

to actuate the electrical discharge means, a stop discharge relay connected in parallel with the trouble signal, and a normally closed single throw stop discharge switch actuated by the stop discharge relay to open the electric discharge means circuit when the trouble signal is actuated.

7. In a smoke detector, a source of electric light, means to conduct a stream of fluid to be tested into the light, supervisory relay means providing trouble indication upon the failure oi the electric light, a resistance in series with the electric light to reduce its intensity and with the supervisory relay means completing a circuit therebetween, and switch means to by-pass the resistance to increase the intensity of the light, whereby the electric light may be intermittently energized at full voltage to provide light for the testing and is continuously energized at low current to provide a supervisory indication of its operativeness.

8. In a smoke detector a source of electric light, means to conduct a stream of fluid to be tested into the light, supervisory relay means providing trouble indication upon the failure of the electric light, a resistance in series with the electric light to reduce its intensity and with the supervisory relay means completing a circuit therebetween, switch means to by-pass the resistance to increase the intensity of the light, and timing means to actuate the switch, whereby the light may be intermittently energized at full voltage to provide light i'orthe testing and is continuously energized at low current to provide a supervisory indication of its operativeness.

9. In a smoke detector, a source of light, means to conduct a stream of fluid to be tested for smoke into the light, a pair of detecing photo-electric means responsive to the presence of smoke in the stream of fluid, each operative between trouble and smoke contacts, a trouble signal, a smoke signal, and switching means actuated by the photo-electric means to operate the trouble signal when either or both of the photo-electric means are operative at their trouble contacts, the switching means actuated by the photo-electric means to indicate the smoke signal only when both of the photo-electric means are operative at their smoke contacts.

10. In a smoke detector, a source of light, means to conduct a stream of fluid to be tested for smoke into the light, a pair of detecting photo-electric means responsive to the presence of smoke in the stream of fluid, relay means electrically connected with each of the detecting photo-electric means, smoke signal contacts for each of the relays connected in series, and switching means, whereby a smoke signal is given only when both of the pair of detecting photo-electric means responds to the presence of smoke.

11. In a smoke detector, light source means, fluid conduction means to bring a stream of fluid to be tested for smoke into the light, a pair of detecting photo-electric means responsive to the presence of smoke in the stream of fluid, a pair of balancing photo-electric means to compensate for variations in the light source, means to electrically connect one of the detecting and one of the balancing photo-electric means in opposition in an electric circuit, an electrical resistance in series with the one detecting and one balancing photo-electric means to minimize the efiect oi the balancing photo-electric means to increase the effectiveness of the detecting photo-electric means a normally closed switch connected across the resistance, the other detecting and balancing cells connected in an opposition circuit, and a relay in said last-mentioned circuit, the relay 0peratively connected to open the normally closed switch, whereby the one detecting photo-electric means is rendered more effective upon the actuation oi the relay by the other detecting photoelectric means.

12. In a smoke detector, a source of light, means to conduct a stream of fluid to be tested for smoke into the light, a pair of detecting photoelectric means responsive to the presence of smoke in the stream of fluid, relay means for the detecting photo-electric means operable between a trouble contact and a smoke contact, a pair of balancing photo-electric means each of which is electrically connected with a detecting photo-electric means and adjusted in the absence of smoke to maintain the relay contacts in a position so that neither trouble nor smoke contacts are completed, switching means adapted to produce a trouble signal when any contact is made, and switching means adapted to nullify the effect of said last-mentioned means when both smoke signal contacts are closed.

13. In a smoke detector, 9. source of light, means to conduct a stream of fluid to be tested for smoke into the light, a pair of detecting photo-electric means responsive to the presence of smoke in the stream of fluid, relay means for the detecting photo-electric means operable between a trouble contact and a smoke contact, a pair of balancing photo-electric means each of which is electrically connected with a detecting photo-electric means and adjusted in the absence of smoke to maintain the relay contacts in a position so that neither trouble nor smoke contacts are completed, switching means adapted to prdouce a trouble signal when any contact is made, switching means adapted to nullify the effect of said last-mentioned means when both smoke signal contacts are closed, and switching means to produce a smoke signal when both smoke contacts are completed.

CLARENCE NOEL CAHUSAC. FRANK B. ALLEN.

References Cited in the file of this patent UNITED STATES PATENTS Number 

